The degenerative brain disease that has besieged the National Football League for two decades with a billion-dollar lawsuit, congressional hearings, an A-list movie and an unrelenting cortege of ex-players’ obituaries has now intruded on America's favorite sport in the most violent manner yet.
The Las Vegas casino worker who killed four people in a New York City skyscraper that is home to the NFL's headquarters carried a note blaming the league for mental health problems he attributed to his time as a high school football player.
